Low Levels of Hepatitis C Virus RNA in Serum, Plasma, and Peripheral Blood Mononuclear Cells of Injecting Drug Users During Long Antibody-Undetectable Periods Before Seroconversion

Fluctuations in serological hepatitis C virus levels in HIV patients

INTRODUCTION

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) have identical transmission routes, explaining the high prevalence of coinfections. The main aim of this study was to detect fluctuations in serological HCV levels in HIV patients.

METHODS

We analyzed samples of 147 patients who attended an outpatient service that supports HIV/AIDS patients in São Paulo city. We also recruited 22 HCV-monoinfected patients who attended the Instituto Adolfo Lutz Laboratory in São Paulo city, to compare the test results. Serological testing of the blood samples was performed for the detection of HCV antibodies. The samples were then analyzed using real-time PCR for RNA viral quantification and sequencing.

RESULTS

We found that 13.6% of the study population was coinfected with HIV and HCV. In 20% of coinfected patients, fluctuations in serology results were detected in samples collected during the follow-up. No changes in anti-HCV serological markers were observed in HCV-monoinfected patients. An HCV viral load was detected in 9,5% of the samples collected from HIV patients.

CONCLUSIONS

Our findings provide important clinical data to public health professionals and highlight the importance of periodic monitoring of HCV/HIV coinfected patients.

Traceability, reproducibility and clinical evaluation of Sansure Realtime HCV RNA assay

Background

Accurate quantitative detection of hepatitis C virus (HCV) RNA is critical for diagnosis of acute or chronic HCV infection, and for follow-up of virologic response during HCV targeted therapy. In the present study, traceability and reproducibility of a novel China-certified domestic Sansure HCV RNA diagnostic assay (Sansure, Changsha, Hunan, China) was evaluated and the clinical performance of this assay was also analyzed.

Methods

Traceability of the Sansure HCV RNA assay to the WHO international standard for HCV (genotype 1a) was detected across multiple centers. Reproducibility, accuracy (the differences of observed average concentrations and expected concentrations) and precision were assessed using series dilutions of World HCV RNA performance panel WWHV303-02 (HCV-1b), WWHV303-04(HCV-2a), WWHV303-11(HCV-3a) and WWHV303-19 (HCV-6a). In addition, both Sansure HCV RNA and CAP/CTM HCV (Roche, Branchburg, NJ, USA) assays were used to detect HCV RNA in 346 EDTA anti-coagulated plasma samples from previous HCV-infected patients, during and after antiviral therapy.

Results

The Sansure assay showed good traceability by agreeing with the HCV-1a WHO standard across all five concentrations tested (25, 50, 100, 1000, 10000 IU/ml). The differences between observed average concentrations and expected concentrations were all within 0.2 log₁₀ IU/ml. HCV WWHV303 standards across 4 HCV genotypes (1b, 2a, 3a and 6a) were used for evaluation of reproducibility and the accuracy of the test were all within 0.2 log₁₀ IU/ml. The inter-assay variations across the above 4 HCV genotypes were all less than 0.03 on each evaluated concentration, indicating good precision of Sansure HCV RNA assay. In clinical practice, concordant results were determined in 99.42 % (344/346) samples (215 positive and 129 negative samples). Two specimens with negative HCV RNA results by Sansure assay were detected positive by CAP/CTM HCV test. Correlation analysis indicated a significantly positive correlation in detected HCV RNA concentrations (r = 0.9439, P < 0.0001). HCV RNA levels in 95.35 % (205/215) specimens were within mean difference ± 1.96 SD as tested by both assays.

Conclusions

With the advantages of traceability, reproducibility and lower price, Sansure HCV RNA assay represented an alternative option for HCV RNA detection in hospital and medical institution in China.

New Hopes for HIV and HCV Coinfection in 2004

An increase in liver-related causes of death in HIV-positive patients who are coinfected with the hepatitis C virus (HCV) has been acknowledged over the last few years, particularly since the mid 1990s, when the natural history of HIV infection started to improve with the use of highly active antiretroviral therapy (HAART). Chronic hepatitis C is very common among HIV-infected patients who were infected through intravenous drugs use or contaminated blood products (e.g., hemophiliacs). The bidirectional interferences between HIV and HCV modify the natural history of both infections. Moreover, interactions between anti-HIV and anti-HCV drugs are of concern, and a lower response to anti-HCV therapy limits its benefit in HIV-coinfected patients. Although a slower HCV RNA decay is seen in coinfected patients after standard therapy is initiated with pegylated interferon plus ribavirin, the stopping rule at week 12 that is recommended for HCV-monoinfected individuals seems to be equally valid in HIV-positive patients. This finding is of great value, because it allows treatment to be offered in the absence of contraindication (e.g., low CD4 count, alcohol abuse, etc.) but discontinued as early as 12 weeks when no chances of cure are predicted, which saves costs and deleterious side effects. HAART therapy seems to temper somehow the negative impact exerted by HIV infection over HCV-related liver fibrosis. Liver transplantation is currently the best option for HIV-infected patients with end-stage liver disease. However, the management of patients on the waiting list and after transplantation carries significant new challenges. New anti-HCV drugs are urgently needed and new strategies with the currently available drugs need to be assessed to reduce the negative impact of hepatitis C in HIV-coinfected individuals.

Detection of HCV-Specific IFN-γ Responses in HCV Antibody and HCV RNA Negative Injecting Drug Users

BACKGROUND

Detectable HCV-specific cellular immune responses in HCV antibody and RNA negative people who inject drugs (PWID) raise the question of whether some are resistant to HCV infection. Immune responses from people who have been exposed to hepatitis C virus (HCV) and remain anti-HCV negative are of interest for HCV vaccine development; however, limited research addresses this area.

OBJECTIVES

In a cohort of HCV antibody and RNA negative PWID, we assessed whether the presence of HCV-specific IFN-γ responses or genetic associations provide any evidence of protection from HCV infection.

PATIENTS AND METHODS

One hundred and ninety-eight participants were examined longitudinally for clinical, behavioral, social, environmental and genetic characteristics (IFNL3 genotype [formally IL-28B] and HLA type). Sixty-one of the 198 participants were HCV antibody and RNA negative, with 53 able to be examined longitudinally for HCV-specific IFN-γ ELISpot T cell responses.

RESULTS

Ten of the 53 HCV antibody and RNA negative participants had detectable HCV-specific IFN-γ responses at baseline (18%). The magnitude of IFN-γ responses averaged 131 +/- 96 SFC/106 PBMC and the breadth was mean 1 +/- 1 pool positive. The specificity of responses were mainly directed to E2, NS4b and NS5b. Participants with (10) and without (43) HCV-specific IFN-γ responses did not differ in behavioral, clinical or genetic characteristics (P > 0.05). There was a larger proportion sharing needles (with 70%, without 49%, P = 0.320) and a higher incidence of HCV (with 35.1 per 100 py, 95% CI 14.6, 84.4, without 16.0 per 100 py, 95% CI 7.2, 35.6, P = 0.212) in those with IFN-γ responses, although not statistically significant. Half the participants with baseline IFN-γ responses became HCV RNA positive (5/10), with one of these participants spontaneously clearing HCV. The spontaneous clearer had high magnitude and broad Th1 responses, favorable IFNL3 genotype and favorable HLA types.

CONCLUSIONS

This study demonstrated the detection of HCV-specific IFN-γ responses in HCV antibody and RNA negative individuals, with a tendency for HCV-specific IFN-γ responses to be associated with HCV exposure. The potential role of HCV-specific IFN-γ responses in those who remained HCV RNA negative is of value for the development of novel HCV therapeutics.

Seronegative hepatitis C virus infection

Hepatitis C virus (HCV) is a major cause of liver disease worldwide. The routine diagnostics identifying HCV infection include testing for specific anti-HCV antibodies by enzyme-linked immnunosorbent assay and viral genetic material in serum or plasma. However, a small proportion of patients persistently infected with HCV, in whom anti-HCV are undetectable, constitute a serious diagnostic and possibly epidemiologic problem, as they could facilitate pathogen spread in the population. This type of infection is termed seronegative or serosilent. Seronegative HCV infection is currently of great interest to both scientists and physicians. The review presents epidemiological data concerning the prevalence of seronegative HCV infection in HIV/HCV co-infected individuals, hemodialysis patients, and blood and organ donors. The possible mechanisms behind this atypical course of infection are discussed. Furthermore, the differences between seronegative and occult infections and prolonged seroconversion are explained.

Implications of hepatitis C viremia vs. antibody alone on transmission among male injecting drug users in three Afghan cities

OBJECTIVES

To assess differences between injecting drug users (IDUs) with hepatitis C virus (HCV) viremia and IDUs with HCV antibody (Ab) or no evidence of prior infection in three Afghan cities.

METHODS

IDUs in Hirat, Jalalabad, and Mazar-i-Sharif completed questionnaires and rapid testing for blood-borne infections including HCV Ab. HCV Ab was confirmed with a recombinant immunoblot assay (RIBA); RIBA-positive specimens underwent reverse transcriptase polymerase chain reaction (RT-PCR) for HCV. Risk behaviors associated with viremia were assessed with site-controlled ordinal regression analysis.

RESULTS

Of 609 participants, 223 (36.6%) had confirmed HCV Ab. Of 221 with serum available for PCR evaluation, 127 (57.5%) were viremic. HCV viremia prevalence did not differ by site (range 41.7-59.1%; p=0.52). Among all IDUs, in age and site-controlled ordinal regression analysis, HCV was independently associated with HIV co-infection (adjusted odds ratio (AOR) 7.16, 95% confidence interval (CI) 4.41-11.64), prior addiction treatment (AOR 1.95, 95% CI 1.57-2.42), ever aspirating and re-injecting blood (AOR 1.62, 95% CI 1.18-2.23), prior incarceration (AOR 1.60, 95% CI 1.04-2.45), and sharing injecting equipment in the last 6 months (AOR 1.35, 95% CI 1.02-1.80).

CONCLUSION

HCV viremia was present in many participants with prior HCV infection and was associated with some injecting risk behaviors, indicating a substantial risk for transmission. Current harm reduction programs should aim to improve HCV awareness and prevention among IDUs in Afghanistan as a matter of urgency.

Incidence and risk factors for community-acquired hepatitis C infection from birth to 5 years of age in rural Egyptian children

A prospective study in three Egyptian villages (A, B and C) having a high prevalence of hepatitis C virus (HCV) infection examined incidence of community-acquired HCV infection in children; 2852 uninfected infants were prospectively followed from birth for up to 5.5 years. Fifteen seroconverted for either HCV antibodies and/or HCV-RNA (incidence of 0.53%). Ten had both anti-HCV and HCV-RNA; four had only anti-HCV; and one had HCV-RNA in the absence of antibody. The incidence rate at all ages was 2.7/1000 person-years (PY). It was 3.8/1000 PY during infancy and 2.0/1000 PY for the 1-5-years age group. Hospitalization and low birth weight increased the risk of infection; while living in village B, the family having a higher socioeconomic status, and advanced maternal education were protective. Six of eight HCV-infected infants reported iatrogenic exposures (e.g. hospitalization, therapeutic injections, ear piercing) prior to infection whereas only 2/7 children older than 1 year reported these exposures. Having an HCV-positive mother was the only other reported risk in two of these older children. The virus cleared in six (40%) children by the end of follow-up. Health education targeting iatrogenic exposures and focusing on risk factors could reduce HCV infection in children in high-risk populations.

Identification of serologically silent occult hepatitis C virus infection by detecting immunoglobulin G antibody to a dominant HCV core peptide epitope

BACKGROUND/AIMS

Occult HCV infection has been described among anti-HCV-HCV RNA-negative individuals with abnormal transaminase values in whom HCV RNA is detected in liver.

METHODS

IgG antibody to an HCVcore-derived peptide (anti-HCVcore) was investigated in 145 patients with serologically silent occult HCV infection.

RESULTS

At the time of the diagnostic biopsy 45/145 (31%) occult HCV-infected patients tested IgG anti-HCVcore-positive but none of the 140 patients with HCV-unrelated liver disease (P<0.001). Among 23 IgG anti-HCVcore-positive patients at baseline, 22 remained antibody-reactive (one became antibody-negative). Similarly, 17/31 baseline anti-HCVcore-negative patients remained non-reactive whereas 14 seroconverted to IgG anti-HCVcore (although transiently in 10 patients). Thus, a total of 59/145 (40.7%) patients with occult HCV infection showed IgG anti-HCVcore reactivity at any time point analyzed, including 14 initially non-reactive patients. By supplemental immunoblot assay 16 sera reacted weakly with an HCVcore-peptide band (indeterminate result) of which 10 (62.5%) reacted in the IgG anti-HCVcore assay. Occult HCV-infected patients who tested anti-HCVcore-positive showed more frequently signs of necro-inflammation (P=0.035) and greater percentages of HCV RNA-positive hepatocytes (P=0.004) compared with those anti-HCVcore-negative.

CONCLUSIONS

This work documents that IgG anti-HCVcore testing identifies occult HCV infection among seronegative, non-viremic patients using screening tests and may be useful in tracking anti-HCV-negative infections.

Hepatitis C virus-specific T-cell immune responses in seronegative injection drug users

T-cell responses to hepatitis C virus (HCV) antigens have been reported in high-risk HCV seronegative persons, suggesting that an effective cellular immune response might be able to clear infection without the development of antibodies. Such findings, however, could be explained by waning antibody or cross-reactivity to other antigens. To address these issues, we evaluated HCV-specific T-cell responses in 26 young (age 18-33 years) aviremic, seronegative injection drug users (IDUs) (median duration of injection, 6 years) by interferon-gamma enzyme-linked immunospot (ELISpot) assay using 429 overlapping HCV peptides pooled in 21 mixes. Seventeen aviremic, seropositive IDUs (spontaneous resolvers) and 15 healthy people were used as positive and negative controls, respectively. The percentage of patients with HCV-specific cellular immune responses was similar in seronegative and seropositive aviremic IDUs (46%vs 59%, P = 0.4), while these responses were not detected in any of the negative controls. Among the seronegative IDUs, six (23%) had intermediate to very strong responses to 10-20 peptide mixes and another six (23%) had moderately strong responses for two to six mixes. The 12 seronegative IDUs with HCV-specific T-cell responses had higher demographical and behavioural risk profiles than the 14 IDUs without T-cell responses (estimated risk of HCV infection, 0.47 vs 0.26, P < 0.01). In conclusion, HCV-specific T-cell responses are common among high-risk, seronegative IDUs. The responses are broad and are associated with risk factors for HCV exposure, suggesting that they reflect true exposure to HCV in seronegative persons.

Prevalence and incidence of hepatitis C in injecting drug users attending genitourinary medicine clinics

Surveillance reports and prevalence studies have indicated that injecting drug users (IDUs) contribute more to the hepatitis C epidemic in the United Kingdom than any other risk group. Information on both the prevalence and incidence of hepatitis C in IDUs is therefore essential to understanding the epidemiology of this infection. The prevalence of hepatitis C in specimens from the Unlinked Anonymous Prevalence Monitoring Programme collected in 1995, 1996, 1998, 1999, 2000, and 2001 was determined using residual syphilis serology specimens from IDUs attending 15 genitourinary medicine (GUM) clinics in and outside London. These specimens were tested for antibodies to hepatitis C virus (anti-HCV). Using this cross-sectional design, anti-HCV-negative specimens were tested for HCV RNA to identify incident infections during the 'window' period of infection, and thus to estimate HCV incidence. Results of the multivariable analysis showed that there was marked variation in prevalence by clinic (P<0.0001) and age (P<0.0001). Overall the majority of infections were in males and the overall prevalence in injectors declined over the study period from 36.9% to 28.7%. The annual incidence in these injectors was estimated as being 3.01% (95% CI 1.25-6.73). Over the study period HCV incidence decreased by 1.2% per year. Genotyping of the incident infections identified the most common genotype as type 1 with type 3 being more frequently seen after 1998. Of the prevalent infections, genotype 1 was the most common. The study has confirmed a higher prevalence of anti-HCV in IDUs in the London area compared to those outside London. How representative of the current injecting drug user population are IDUs attending GUM clinics is unclear. Even so, such studies allow prevalence and incidence to be estimated in individuals who have ever injected drugs and inform ongoing public health surveillance.

Incidence and risk factors for hepatitis C infection in a cohort of women in rural Egypt

A prospective cohort study of the incidence and risk factors for hepatitis C virus (HCV) infection was performed in 2171 pregnant women in three rural Egyptian villages who were HCV antibody (anti-HCV) and RNA (HCV-RNA) negative at baseline. During an average of 2.2 years follow up, 25 incident cases were observed, giving an estimated HCV incidence of 5.2/1000 person-years (PY). The infection rate correlated with community anti-HCV prevalence in pregnant women, while the perinatal incidence rate of 11.2/1000 PY was almost five times that of the non-perinatal rate (2.3/1000 PY). The data suggested iatrogenic perinatal risk factors were associated with infection in one village, while health education reduced infections in another. Among the 25 incident cases, eight were HCV-RNA negative when they were first found to be anti-HCV positive and one-third of the 15 viraemic cases with follow-up data available cleared their HCV-RNA after an average of 1.3 years. None of the 25 incident cases were jaundiced or had symptoms of hepatitis but elevated serum alanine aminotransferase levels confirmed hepatitis in nine. Our data suggest that asymptomatic HCV infections frequently occurred during the perinatal period but often cleared and that educating medical personnel on safe practices possibly reduced HCV transmission.

HCV-specific T-cell responses in injecting drug users: evidence for previous exposure to HCV and a role for CD4+ T cells focussing on nonstructural proteins in viral clearance

In order to understand the parameters associated with resolved hepatitis C virus (HCV)-infection, we analysed the HCV-specific T-cell responses longitudinally in 13 injecting drug-users (IDUs) with a prospectively identified acute HCV infection. Seven IDUs cleared HCV and six IDUs remained chronically infected. T-cell responses were followed in the period needed to resolve and a comparable time span in chronic carriers. Ex vivo T-cell responses were measured using interferon-gamma Elispot assays after stimulation with overlapping peptide pools spanning the complete HCV genome. CD4+ memory-T-cell responses were determined after 12-day stimulation with HCV proteins. The maximum response was compared between individuals. The T-cell responses measured directly ex vivo were weak but significantly higher in resolvers compared to chronic carriers, whereas the CD4+ memory-T-cell response was not different between resolvers and chronic carriers. However, HCV Core protein was targeted more often in chronic carriers compared to individuals resolving HCV infection. CD4+ T-cell responses predominantly targeting nonstructural proteins were associated with resolved HCV infection. Interestingly, observation of memory-T-cell responses present before the documented HCV-seroconversion suggests that reinfections in IDUs occur often. The presence of these responses however, were not predictive for the outcome of infection. However, a transition of the HCV-specific CD4+ memory-T-cell response from targeting Core to targeting nonstructural proteins during onset of infection was associated with a favourable outcome. Therefore, the specificity of the CD4+ memory-T-cell responses measured after 12-day expansion seems most predictive of resolved infection.

Hepatitis C virus lymphotropism: lessons from a decade of studies

The possibility that HCV infects lymphoid cells has been widely discussed. Evidence in favor of HCV tropism for lymphoid cells derives from a series of data including: (1) the higher sensitivity of testing HCVRNA in PBMC than in serum or plasma samples, with possible detection of HCV RNA-positive PBMC in the absence of HCV viremia; (2) short-term cultures of PBMC which yield a significant increase in the amount of viral RNA on stimulation by mitogens; (3) results of "in situ" methods (i.e. in situ hybridization, immunofluorescence); (4) efficient infection of lymphoid cell lines or PBMC from normal individuals; (5) the persistence of HCV RNA in PBMC obtained from HCV-positive subjects and injected into SCID mice; (6) the long-term persistence of HCV RNA in PBMC in spite of HCV RNA negativity of serum and liver in sustained responder patients after therapy. The principal criticisms concerning effective HCV infection of lymphoid cells arise from technical difficulty in identifying HCV RNA replicative intermediate in these elements. Conflicting data may also result from differences in PBMC infection by different genotypes, samples taken at different stages in the disease process and differences in the sensitivity of detection methods, as well as low replication levels and/or proportion of infected PBMC. Interesting available data about HCV lymphotropism, which is possibly important in influencing the natural history of infection, include: (1) possible preferential viral tropism for specific PBMC subsets; (2) different lymphotropism of different viral strains; (3) selection of distinctive viral strains; (4) identification of putative HCV cell receptors; (5) association between determination of HCV lymphatic infection and t(14; 18) translocation. The clinical correlates of HCV lymphotropism are potentially very numerous, including, first, its role in determining HCV-related lymphoproliferative disorders.

High levels of subgenomic HCV plasma RNA in immunosilent infections

A genetic analysis of hepatitis C virus (HCV) in rare blood donors who remained HCV seronegative despite long-term high-level viremia revealed the chronic presence of HCV genomes with large in frame deletions in their structural genes. Full-length HCV genomes were only detected as minority variants. In one immunodeficiency virus (HIV) co-infected donor the truncated HCV genome transiently decreased in frequency concomitant with delayed seroconversion and re-emerged following partial seroreversion. The long-term production of heavily truncated HCV genomes in vivo suggests that these viruses retained the necessary elements for RNA replication while the deleted structural functions necessary for their spread in vivo was provided in trans by wild-type helper virus in co-infected cells. The absence of immunological pressure and a high viral load may therefore promote the emergence of truncated HCV subgenomic replicons in vivo.

Host and viral factors in the immunopathogenesis of primary hepatitis C virus infection

Individuals infected with hepatitis C virus (HCV) have two possible outcomes of infection, clearance or persistent infection. The focus of this review is the host mechanisms that facilitate clearance. The interaction between HCV viral components and the immune system ultimately determines the balance between the virus and host. Strong evidence points to the aspects of cellular immune response as the key determinants of outcome. The recent discovery of viral evasion strategies targeting innate immunity suggests that the interferon-alpha/beta induction pathways are also critical. A growing body of evidence has implicated polymorphisms in both innate and adaptive immune response genes as determinants of viral clearance in individuals infected with HCV.

Interferon regulatory factor-1 promoter polymorphism and the outcome of hepatitis C virus infection

OBJECTIVE

Interferon-alpha (IFN-alpha), an important mediator for the host's innate antiviral defense system, has been approved for the treatment of persistent viral infections. We investigated whether two functional polymorphisms in genes involved in IFN-alpha signaling and effector functions are associated with the natural outcome of hepatitis C virus (HCV) infection and the responsiveness of chronic hepatitis C patients to IFN-alpha therapy.

METHODS

Forty-four individuals who had resolved HCV infection spontaneously and 147 patients who developed chronic hepatitis C were analyzed for functional single nucleotide polymorphisms in the promoter regions of the interferon regulatory factor-1 (IRF-1) and myxovirus resistance protein-1 (MxA) genes at positions -300 and -88, respectively.

RESULTS

With regard to -300 IRF-1 or -88 MxA genotype distributions or minor allele frequencies, individuals who spontaneously resolved the infection displayed no significant difference compared with those with chronic infections. Among patients with chronic infections, however, the -300AA IRF-1 genotype, associated with a higher IRF-1 transcriptional activity, was absent in patients with chronic HCV genotype 3a infections, with one exception. In contrast to expectations, -300AA IRF-1 individuals with HCV genotype 3a infection were not represented in higher numbers among those with self-limited infections. Regarding IFN-alpha therapy, -300AA IRF-1 chronic hepatitis C genotype 1 patients tend to respond more often than those with the other IRF-1 genotypes.

CONCLUSION

Our findings suggest the possibility that the -300AA IRF-1 genotype is associated with outcome in patients with HCV genotype 3 infection. In addition, in HCV genotype-1-infected patients, this genotype appears associated with response to therapy.

[HIV and HCV coinfection]

Chronic hepatitis due to hepatitis C virus (HCV) infection is now one of the leading causes of morbidity and mortality among HIV-infected individuals. Coinfected patients present an accelerated course toward cirrhosis and an enhanced risk of liver toxicity associated with the use of antiretroviral agents. Treatment of chronic hepatitis C in HIV1 patients is less efficacious than in HCV-monoinfected individuals and requires particular expertise.

Protective immunity against hepatitis C virus infection

There is increasing evidence that a small percentage of individuals exposed to the hepatitis C virus have the capacity to generate a strong cellular immune response against the virus and avoid persistent infection, and perhaps do so repeatedly after re-exposure. This article reviews the evidence that the responses identified in this unique group of individuals represent the protective immunity that will need to be elicited by hepatitis C virus vaccines.

HIV-related liver disease: infections versus drugs

HIV-infected individuals have myriad causes of hepatotoxicity that range from mild hepatitis to significant liver failure with its associated morbidity and mortality, especially in the setting of chronic viral hepatitis (HCV and HBV). Immune restoration by HAART therapy can contribute liver-related toxicity in HIV-coinfected patients. Clinicians need to be aware of this problem and individualize management in this challenging clinical scenario. Avoidance of potentially hepatotoxic agents or close monitoring during treatment of HIV may prevent liver failure in patients who have HIV. Furthermore, vaccination against hepatitis A virus and HBV in nonimmune HIV individuals may prevent acquisition of hepatitis A virus and HBV infections in patients who have HIV. Finally, treatment of HIV, and, if appropriate, treatment of those who are coinfected with HCV and HBV with close monitoring, may improve the outcome of patients who have HIV and are at risk fo r significant hepatotoxicity during treatment from immune restoration or hypersensitivity reactions.

New paradigms in the management of HIV and hepatitis C virus coinfection

PURPOSE OF REVIEW

Chronic hepatitis C virus infection is currently one of the leading causes of morbidity and mortality in HIV-infected individuals, mainly in hemophiliacs and intravenous drug users. The bidirectional interferences between hepatitis C virus and HIV have clinical consequences and complicate the management of coinfected individuals.

RECENT FINDINGS

There is an increased rate of liver complications among coinfected patients due to the decrease in opportunistic infections resulting from the use of potent antiretroviral therapy and accelerated progression to liver cirrhosis in the HIV setting. Conversely, the risk of hepatotoxicity of antiretrovirals is higher in the presence of chronic hepatitis C. While the standard therapy for hepatitis C in HIV is the combination of pegylated interferon plus ribavirin, overall treatment responses are lower in HIV-coinfected than in hepatitis C virus-monoinfected patients. Moreover, interactions between ribavirin and HIV drugs (i.e. didanosine, zidovudine) are associated with higher risks of side effects.

SUMMARY

Given the accelerated progression to end-stage liver disease in coinfected patients, treatment of hepatitis C should be a priority. While hepatitis C therapy should not be denied in the absence of contraindication, it should be re-assessed at week 12 and therapy continued only in patients showing more than 2 log drops in viremia, to avoid side effects. Most recent data suggest that adequate selection of candidates, expert management of side effects, and prescription of appropriate ribavirin doses (in genotypes 1-4) and extending treatment (in genotypes 2-3) all might allow response rates in coinfected patients to approach those seen in hepatitis C virus-monoinfected individuals.

Role of nucleic acid testing in cadaver organ donor screening: detection of hepatitis C virus RNA in seropositive and seronegative donors

Hepatitis C virus (HCV) transmission by both seropositive and seronegative cadaver organ donors has been documented, yet nucleic acid testing is not routinely used to identify active infection in these donors prior to transplantation. Between November 2001 and February 2004, we screened 1445 cadaver organ donors for anti-HCV antibodies with either HCV EIA-2.0 (Abbott Diagnostics, Chicago, IL, USA) and/or Ortho HCV Version 3.0 ELISA (Ortho-Clinical Diagnostics, Raritan, NJ, USA) and confirmed seropositive samples with Chiron RIBA3.0 SIA (Chiron Corporation, Emeryville, CA, USA). Samples with sufficient volume (n = 726) were tested by the VERSANT HCV [transcription-mediated amplification (TMA)] Qualitative assay (Bayer Healthcare LLC, Tarrytown, NY, USA) which can be performed in approximately 5 h. Those with detectable HCV RNA and sufficient volume were quantified by the VERSANT HCV 3.0 (bDNA) Assay (Bayer Healthcare LLC) and/or the HCV RNA TMA Quantitative Assay (n = 23) and genotyped (n = 57). Seventy-seven of 1445 (5.3%) donors were seropositive, reactive by either one or both anti-HCV assays. Fifty-two of 63 (82.5%) of the seropositive samples had detectable HCV RNA and were genotyped. Seventeen of these samples had quantifications ranging from 128,123 to >7,692,307 IU/mL. Six of 663 (0.9%) seronegative samples had detectable HCV RNA. Their quantifications ranged from <9.3 to 1,464,799 IU/mL, and five of these six were successfully genotyped. As HCV RNA was demonstrated in samples from both our seropositive and seronegative cadaver organ donors, we are now incorporating nucleic acid testing into our donor screening/diagnostic algorithm.

Dynamics of viremia in early hepatitis C virus infection

BACKGROUND

It is important to characterize viral dynamics in early hepatitis C virus (HCV) infection to further our understanding of viral pathogenesis and the potential for secondary transmission in acute infection through blood transfusion or other routes.

STUDY DESIGN AND METHODS

Serial units given by 77 source plasma donors who had evolved from HCV RNA-negative to HCV RNA-positive by nucleic acid amplification technology (NAT) screening with 512-unit pool-NAT or were followed from RNA detection to antibody conversion were tested by individual NAT and quantitative RNA assays.

RESULTS

During the ramp-up phase when exponential growth occurs, HCV viral load doubled every 10.8 hours (95% confidence interval [CI], 9.9-12.0). Intermittent viremia was observed before the ramp-up phase in 37 of 50 panels with the earliest detectable viremic bleed occurring 63 days before the estimated onset of ramp-up. The plateau phase or high-titer viremic period that occurs between ramp-up and seroconversion was estimated to last 56.3 days (95% CI, 44.8-67.8).

CONCLUSIONS

Intermittent low-level HCV viremia can occur as much as 2 months before the periods of exponential increase in viral load and the high-titer plateau-phase viremia that usually precede seroconversion. Animal inoculation studies are in progress to evaluate if transfusion of low-level viremic plasma can transmit HCV infection.

Increased sensitivity of the Roche COBAS AMPLICOR HCV test, version 2.0, using modified extraction techniques

Processing modifications were made to the COBAS AMPLICOR HCV version 2.0 assay to enhance sensitivity. Two methods of specimen concentration, centrifugation ("ultraspin") and cationic detergent plus silica membrane ("ultracolumn"), were compared to the standard method. The effect of these changes on assay sensitivity and specificity was examined using commercial hepatitis C virus (HCV) preparations. The limits of detection (LOD, defined as detection of HCV RNA in >/= 95% of replicates) of genotype 1a were 50, 12, and 6 by standard method, ultraspin and ultracolumn, respectively. For genotype 1b, the LOD was 25 IU/ml, 12 IU/ml, and 3 IU/ml; for 2b, it was 50, 12, and 3; for 3a, it was 25, 12, and 1.5; for 4 it was 18, 4, and 2; for 5a, it was 38, 9, and 2; and for 6a it was 47, 6, and 3. No false positives were detected after ultraspin when controls containing high or low HCV concentrations were alternated with normal human plasma. Plasmas in which HCV RNA was not detected by the standard assay were re-tested with modified methods to assess the effect of altered processing in clinical specimens. Three of 152 specimens with no detectable HCV RNA by the standard method were positive by ultraspin and 2 of 109 were positive by ultracolumn, suggesting that these methods may increase assay sensitivity in clinical specimens.

Influence of hemodialysis procedure on HCV RNA detection in serum and peripheral blood mononuclear cells

AIM

To assess whether hemodialysis procedure induces qualitative or quantitative changes in hepatitis C virus (HCV) RNA.

METHODS

We obtained blood samples in the 10 HCV RNA-positive patients of our hemodialysis unit before (sample I) and 5 min after a dialysis session (sample II), and before the next dialysis session (sample III). HCV RNA was tested by PCR in serum and peripheral blood mononuclear cells (PBMC). Serum viral load was measured by branched-DNA assay.

RESULTS

Serum HCV RNA was positive in samples I, II and III of the 10 patients. PBMC HCV RNA was detected in samples I, II and III of seven patients. Mean viral load was 1.43+/-0.99 Meq genome/mL in sample I, 0.86+/-0.40 Meq genome/mL in sample II and 1.27+/-0.56 Meq genome/mL in sample III.

CONCLUSIONS

HCV load was low in most HCV RNA-positive patients. It had a downward trend during dialysis procedure but HCV RNA remained detectable in all serum samples and in most PBMC samples. Therefore, qualitative HCV RNA seems to be better than viral load to assess HCV infection in hemodialysis patients.

Detection of HIV-1 and HCV infections among antibody-negative blood donors by nucleic acid-amplification testing

BACKGROUND

Testing of blood donors for human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) RNA by means of nucleic acid amplification was introduced in the United States as an investigational screening test in mid-1999 to identify donations made during the window period before seroconversion.

METHODS

We analyzed all antibody-nonreactive donations that were confirmed to be positive for HIV-1 and HCV RNA on nucleic acid-amplification testing of "minipools" (pools of 16 to 24 donations) by the main blood-collection programs in the United States during the first three years of nucleic acid screening.

RESULTS

Among 37,164,054 units screened, 12 were confirmed to be positive for HIV-1 RNA--or 1 in 3.1 million donations--only 2 of which were detected by HIV-1 p24 antigen testing. For HCV, of 39,721,404 units screened, 170 were confirmed to be positive for HCV RNA, or 1 in 230,000 donations (or 1 in 270,000 on the basis of 139 donations confirmed to be positive for HCV RNA with the use of a more sensitive HCV-antibody test). The respective rates of positive HCV and HIV-1 nucleic acid-amplification tests were 3.3 and 4.1 times as high among first-time donors as among donors who gave blood repeatedly. Follow-up studies of 67 HCV RNA-positive donors demonstrated that seroconversion occurred a median of 35 days after the index donation, followed by a low rate of resolution of viremia; three cases of long-term immunologically silent HCV infection were documented.

CONCLUSIONS

Minipool nucleic acid-amplification testing has helped prevent the transmission of approximately 5 HIV-1 infections and 56 HCV infections annually and has reduced the residual risk of transfusion-transmitted HIV-1 and HCV to approximately 1 in 2 million blood units.

Failure to diagnose recent hepatitis C virus infections in London injecting drug users

Hepatitis C virus (HCV) infection results in chronic liver disease in a substantial proportion of those infected. Most new cases of HCV infection in the UK are associated with intravenous drug use. It is important to identify these infections because of the implications for the future health of the individuals concerned and for the control of further spread of infection. However, as hepatitis C infection is characterised by a relatively long asymptomatic period of seronegative viraemia, a laboratory diagnostic protocol that does not test HCV seronegative samples for the presence of HCV RNA may wrongly designate HCV viraemic seronegative individuals as uninfected. Amongst 424 injecting drug users whose serum was sent to our diagnostic laboratory for "HCV screening" over a 14-month period, the prevalence of HCV seropositivity was 48.4%. We retrospectively identified seven individuals for whom there was evidence of recent acquisition of HCV infection. Three of these infections were identified using our routine diagnostic protocol: testing for the presence of HCV-specific antibody and performing HCV RNA testing only on seropositive and seroindeterminate specimens. However, four cases were only identified by HCV RNA testing of HCV seronegative serum. On the basis of these observations, we estimate the incidence of HCV infection amongst London injecting drug users as being 14.3 per 100 person-years. We advocate that all HCV seronegative blood samples obtained from injecting drug users should be tested for the presence of HCV RNA, and suggest that this could be done efficiently by nucleic acid testing the specimens in small pools. .

Piezoelectric biosensors for real-time monitoring of hybridization and detection of hepatitis C virus

The piezoelectric quartz crystal resonators modified with oligonucleotide probes were used for detection of hepatitis C virus (HCV) in serum. The gold electrodes on either rough or smooth surface crystals were modified with a self-assembled monolayer of cystamine. After activation with glutaraldehyde, either avidin or streptavidin were immobilized and used for attachment of biotinylated DNA probes (four different sequences). Piezoelectric biosensors were used in a flow-through setup for direct monitoring of DNA resulting from the reverse transcriptase-linked polymerase chain reaction (RT-PCR) amplification of the original viral RNA. The samples of patients with hepatitis C were analyzed and the results were compared with the standard RT-PCR procedure (Amplicor test kit of Roche, microwell format with spectrophotometric evaluation). The piezoelectric hybridization assay was completed in 10 min and the same sensing surface was suitable for repeated use.

Hepatitis C Infection: A Clinical Review

Nearly three million persons in the United States are viremic with hepatitis C (HCV). Despite a decreasing incidence of HCV in this country, the prevalence of HCV-related chronic liver disease is increasing. Most infections in the United States are acquired by intravenous drug use. The chronicity rate of HCV is high, reaching 85% in some populations, and the risk of progression to advanced liver disease is as high as 20% within twenty years of infection. Host factors like alcohol use accelerate the rate of progression. The enzyme immunoassay is the preferred initial test for diagnosis; the third generation assay has greater than a 99% specificity in immunocompetent patients. Barring contraindications, the standard of care for treatment of chronic HCV has become pegylated interferon and ribavirin. With this therapy, the cure rate for treatment-naïve patients is about 55%, but rates are higher in certain groups. Common side effects of therapy include neuropsychiatric symptoms, influenza-like symptoms and hematological abnormalities.

Clinical evaluation of an HIV-1 and HCV assay and demonstration of significant reduction of the HCV detection window before seroconversion

BACKGROUND

One HIV-1 and HCV assay simultaneously detects HIV-1 and HCV RNA (Procleix, Chiron Corp.). The main intended use of the assay is the testing of blood and blood products in blood banking.

STUDY DESIGN AND METHODS

To evaluate the clinical sensitivity of the assay, 164 anti-HIV-1+ and 160 anti-HCV+ patients of different viral load were tested. The assay specificity was determined in 1000 HIV-1- and HCV-seronegative blood donors. The ability of the assay to detect different HCV genotypes was investigated in a total of 40 patients of different genotypes (1-4). Furthermore, to investigate the reduction of the HCV window phase before seroconversion, serial samples of 25 hemodialysis patients who seroconverted to anti-HCV were also tested.

RESULTS

The assay detected all 60 HIV-1-infected patients with a viral load of greater than 50 copies per mL and 48 of 104 patients with a viral load of less than 50 copies per mL. Moreover, all 60 patients with an HCV RNA load of greater than 521 IU per mL and 7 of 100 patients with a viral load of less than 50 IU per mL tested positive. The assay specificity was found to be 100 percent. In addition, all 40 patients of different HCV genotypes were successfully detected. Finally, the median time that the assay detected HCV infection before second- and third-generation anti-HCV assay was found to be 183 and 91 days, respectively.

CONCLUSION

The assay sensitivity and specificity, its ability to detect different HCV genotypes, and the significant reduction of window period of HCV infection further support its use for improving the safety of blood and blood products.

Prospective study of hepatitis C virus infection in hemodialysis patients by monthly analysis of HCV RNA and antibodies

The aims of this study were to (i) evaluate the prevalence and the incidence of hepatitis C virus (HCV) infection in hemodialysis patients in two different centers in São Paulo (Brazil), (ii) determine the time required to detect HCV infection among these patients by serology or PCR, (iii) establish the importance of alanine aminotransferase determination as a marker of HCV infection, and (iv) identify the HCV genotypes in this population. Serum samples were collected monthly for 1 year from 281 patients admitted to hospital for hemodialysis. Out of 281 patients, 41 patients (14.6%) were HCV positive; six patients seroconverted during this study (incidence = 3.1/1000 person-month). In 1.8% (5/281) of cases, RNA was detected before the appearance of antibodies (up to 5 months), and in 1.1% (3/281) of cases, RNA was the unique marker of HCV infection. The genotypes found were 1a, 1b, 3a, and 4a. The presence of genotype 4a is noteworthy, since it is a rare genotype in Brazil. These data pointed out the high prevalence and incidence of HCV infection at hemodialysis centers in Brazil and showed that routine PCR is fundamental for improving the detection of HCV carriers among patients undergoing hemodialysis.

Occult hepatitis C virus infection in type II mixed cryoglobulinaemia

Mixed cryoglobulinaemia, when not secondary to other well-defined immunological disorders, is commonly associated with hepatitis C virus (HCV) infection. However, a minority of cases lack evidence of HCV infection and are, therefore, defined as 'true essential' mixed cryoglobulinaemias. We thoroughly investigated three such patients to determine the aetiology of this disorder. Antibodies to HCV (anti-HCV) and HCV RNA, detected by sensitive enzyme-linked immunosorbent and polymerase chain reaction assays in serum and in concentrated cryoglobulins, were repeatedly negative in the three patients. Despite the lack of evidence for HCV infection, two of them were still treated with interferon alpha-2a assuming unrecognized viral infection. Both patients demonstrated excellent clinical and laboratory responses, but cryoglobulinaemia relapsed after the withdrawal of therapy. At the time of relapse, HCV RNA genomic sequences were detected for the first time in the cryoprecipitates of both patients. In the third case, HCV RNA was demonstrated for the first time during a flare of cryoglobulinaemia coincident with varicella infection. In all three patients anti-HCV antibodies remained negative throughout follow-up. We conclude that some apparently 'essential' forms of mixed cryoglobulinaemia can be caused by occult HCV infection. Interferon therapy can be taken into consideration in such HCV-negative cases.

Incident hepatitis C virus in women with human immunodeficiency virus infection

Individuals infected with human immunodeficiency virus type 1 (HIV-1) are frequently coinfected with hepatitis C virus (HCV). Acute HCV infection is often asymptomatic and poorly understood. We conducted a historical prospective study of HCV antibody and viremia in plasma samples obtained during 1994-1999 from a cohort of initially HIV-1-infected, HCV-uninfected women and from HIV-1-HCV-uninfected women. Twenty-two (1.5%) of 1517 experienced seroconversion. Of these, 14 (64%) truly acquired a new infection as assessed by enzyme immunoassay response and new-onset viremia. The incidence rate in HIV-1-infected women was 2.7 cases per 1000 person-years; it was 3.3 cases per 1000 person-years in HIV-1-seronegative women (relative risk, 1.21; P=.75). Acquisition of HCV was associated with any history of drug use (P<.01). Five of 12 viremic, seroconverting individuals cleared viremia. Incident HCV infection among HIV-1-infected and HIV-1-uninfected women was low. It was linked to drug use and commonly resolved.

HCV viral load in anti-HCV-reactive donors and infectivity for their recipients

BACKGROUND

An attempt has been made to determine the minimum level of HCV nucleic acid in donors associated with infection of recipients. This is important for considerations about assay sensitivity, use of minipool versus single-donation testing, and continued use of serologic testing.

STUDY DESIGN AND METHODS

A total of 5387 specimens from the Transfusion-Transmitted Viruses Study in the 1970s were screened for antibody to HCV (anti-HCV). The outcome in recipients of seroreactive donations was examined for viremia and seroconversion. Present techniques for both groups included third-generation EIA, RIBA, quantitative RT-PCR assay, and transcription-mediated amplification (TMA) assay.

RESULTS

A total of 156 recipients of components from 180 anti-HCV-reactive donors were identified. One-hundred seven of these were HCV-naïve before transfusion and received a single, confirmed seropositive unit; 94 (88%) became infected. Eighty-five recipients had donors whose HCV RNA level was quantifiable by RT-PCR (range, 182-3,310,000 copies/mL). Eighty-three (98%) seroconverted. Of the remaining 22, a total of 10 received units positive for HCV RNA detected only by TMA; all 10 recipients seroconverted. Of the remaining 12 recipients of anti-HCV+, TMA-negative units, 1 recipient seroconverted.

CONCLUSIONS

High rates of transmission were seen at all levels of viremia, and one donor transmitted with undetectable levels in the TMA assay. Current HCV RNA testing will therefore not interdict all infectious units, even with single-donation testing, and serologic screening must be continued.

Detection of a healthy carrier of HCV with no evidence of antibodies for over four years

BACKGROUND

Posttransfusion HCV has been notably reduced over recent years as a result of the systematic testing for antibodies to HCV in blood donors. However, the risk of transfusing blood-derived components from virus-carrying donors still remains. A diagnosis is reported here of HCV in a regular blood donor who had no antibodies during the entire time she was followed up.

CASE REPORT

The pharmaceutical company responsible for fractioning the plasma detected a donor who was a carrier of HCV, confirmed by PCR, but whose tests to detect anti-HCV were systematically negative. The donor had given blood on five previous occasions, from which 14 components were manufactured. Of the 11 components traced, six had been transfused, and in the two cases in which study of the anti-HCV was possible in the recipients, the result was positive. It was possible to check the blood samples from the donor from May 1997 to March 2002 (58 months). The tests to detect anti-HCV were all negative, while the PCR and core antigen tests were positive.

CONCLUSION

The incorporation of RNA detection or HCV core antigen techniques in blood banks may reduce the residual risk of contracting posttransfusion HCV. Measures such as the correct traceability of the components, the existence of a specimen bank, or follow up of the recipients of blood-derived components would help to improve the quality of blood banking with percentage of survivability and case investigations.

Evaluation of a transcription-mediated amplification-based HCV and HIV-1 RNA duplex assay for screening individual blood donations: a comparison with a minipool testing system

BACKGROUND

NAT was introduced for HCV RNA in 1999 to screen blood donations and improve the safety of the blood supply.

STUDY DESIGN AND METHODS

The performance of a NAT multiplex for HCV and HIV-1 RNA based on transcription-mediated amplification (TMA) was assessed with various sensitivity panels and by screening 50,000 serologically unscreened, first-time donor plasma samples. Results were compared with a routine NAT screening for HCV RNA by RT-PCR in pools of 96 plasma samples.

RESULTS

The TMA multiplex 95 percent sensitivity ranged between 22 and 54 IU per mL for HIV-1 and 15 and 20 IU per mL for HCV RNA. The rate of test failure was 8.6 percent but decreased to 4.7 percent when results of two critical periods of equipment malfunction were excluded. Test failure was related to human error, minute control contamination, and insufficient mixing of reagents at the extraction stage. All 31 repeatedly reactive samples (0.06%) were seropositive for HCV (29) or HIV-1 (2) and contained RNA detectable by discriminatory TMA and confirmatory RT-PCR, indicating 100 percent specificity. A direct comparison of TMA in individual samples and RT-PCR in plasma pools was possible on 27 HCV RNA-containing samples. Twenty-six samples were detected in plasma pools; the lack of detection of 1 sample was due to an identification error at the pooling stage.

CONCLUSION

The HCV and HIV-1 multiplex NAT had high specificity and sensitivity.

Sensitivity of HCV core antigen and HCV RNA detection in the early infection phase

BACKGROUND

Various countries have introduced HCV NAT to exclude infectious donations collected during the preseroconversion window phase (PWP). For the same purpose, an ELISA has also been developed to detect HCV core antigen (cAg).

STUDY DESIGN AND METHODS

Using sequential samples from regular plasma donors with very recent HCV infections, a total of 494 samples from 52 anti-HCV-negative donors were collected. These panels were used for direct comparison of the performance of PCR and ELISA in detecting viral markers (RNA and cAg) during the PWP of HCV infection. The panels were genotyped, and each sample was analyzed by qualitative and quantitative HCV PCR and by cAg ELISA. The HCV RNA doubling time was calculated from quantitation of viral RNA in consecutive samples during the earliest outbreak of viremia.

RESULTS

Concurrent detection of HCV RNA and cAg in 218 and nondetection in 185 samples yielded 81.6-percent concordance in the results of 494 samples. Unidirectional discrepancy of results (i.e., PCR positive and cAg negative) was seen in 91 of 494 (18.4%) samples, which was consistent with 65 specimens with RNA concentrations ranging between 300 and 100,000 IU per mL and 26 specimens with less than 300 IU per mL (limit of quantitative PCR). Individual genotyped panels had different kinetics and courses of viremia. The mean doubling time in the early PWP at the onset of viremia was derived to be 10.8 (range, 5.8-21.0) hours.

CONCLUSION

A majority of HCV RNA-positive samples were also cAg-positive during the PWP. The current cAg detection corresponds to 100,000 IU per mL of HCV RNA. Since low-titer samples would be identified only by single-donation NAT, which is often affordable only in developed countries, the cAg ELISA could offer a practical alternative for some countries. The doubling time for HCV RNA at the onset of viremia corresponds to a calculated mean delay of cAg detection during the virus burst phase of 2 or 5 days, when compared with minipool (5000 IU/mL) or single-donation NAT (50 IU/mL), respectively.

Seroprevalence of hepatitis C markers among intravenous drug users in western European countries: a systematic review

Currently, the most important risk factor for hepatitis C virus (HCV) infection in Europe is intravenous drug use. To establish a better insight into the epidemiology of hepatitis C among intravenous drug users (IVDUs) in western European countries a systematic review on the prevalence of hepatitis C markers and their determinants was performed. Reports were identified by searches on Medline and on the internet and by screening reference lists of selected papers. The prevalence rates of anti-HCV in western European IVDUs reported in the 66 studies selected for analysis, ranged between 37 and 98%. No relation was found between prevalence rates and mean age, mean duration of intravenous drug use, geographical area, setting of the study, method of recruitment or the year(s) of collection of samples. Eleven studies concerning the prevalence of HCV-RNA in hepatitis C-infected IVDUs were selected for analysis. Prevalence rates ranged from 26 to 86%. Based on five studies, a statistically significant positive linear relation was found between the mean age of study population and the prevalence of HCV-RNA. Our analysis revealed considerable variation in prevalence rates of hepatitis C markers among IVDUs in western Europe. We found no conclusive explanation for this variability. Further research investigating the dynamics of the hepatitis C epidemic in IVDUs is necessary.

Immunopathogenesis of hepatitis C virus infection

Hepatitis C virus, a recently identified member of the family Flaviviridae, is an important cause of chronic viral hepatitis and cirrhosis. There are similarities in the nature of the immune response to this pathogen with immunity in other flavivirus and hepatotropic virus infections, such as hepatitis B. However, the high rate of viral persistence after primary hepatitis C infection, and the observation that neutralizing antibodies are not protective, would suggest that there are a number of important differences between hepatitis C, other flaviviruses, and hepatitis B. The phenomenon of quasispecies evolution and other viral factors have been proposed to contribute to immune evasion by hepatitis C virus. In the face of established persistent infection, virus-specific cytotoxic T lymphocytes may exert some control over viral replication. However, these same effectors may also be responsible for the progressive liver damage characteristic of chronic hepatitis C infection. The nature of protective immunity, including the role of innate immune responses early after hepatitis C exposure, remains to be defined.

Lack of seroconversion in a health care worker after polymerase chain reaction-documented acute hepatitis C resulting from a needlestick injury

We present a case of documented acute hepatitis C that occurred in a health care worker who sustained a needlestick injury while caring for an individual who was infected with both hepatitis C virus (HCV) and human immunodeficiency virus (HIV). According to the findings of third-generation serological assays performed during a follow-up of >1 year, the health care worker, who was treated with interferon-alpha (during weeks 2-6) and ribavirin (during weeks 5-9), did not develop antibodies against HCV, in spite of documentation of an HCV-specific T cell response.

A novel RT-PCR for reliable and rapid HCV RNA screening of blood donations

BACKGROUND

The objective of this work was to develop a novel and highly sensitive RT-PCR method that is suitable for HCV RNA screening of blood donations according to the criteria released by the Paul Ehrlich Institute, the federal licensing agency of Germany, for routine HCV NAT.

STUDY DESIGN AND METHODS

RNA was prepared from plasma pools of up to 20 single blood donations using an automated nucleic acid isolation system (NucliSens Extractor, Organon Teknika). For reverse transcription, amplification, and simultaneous detection of PCR products, a novel approach based on the TaqMan technology was developed. Glyceraldehyde-3-phosphate dehydrogenase messenger RNA, which is detectable in human plasma, was coamplified in each reaction as an internal positive control.

RESULTS

The HCV genotypes and subtypes 1a, 1b, 2a, 2b, 2c, 2i, 3a, 4, and 5a were detected in parallel with comparable amplification efficiency. The 95-percent detection limit related to the WHO HCV RNA standard preparation was calculated to be 389 IU per mL of plasma of the single blood donation. Total CVs (%) were <4. The screening of up to 180 blood donations took 5 hours; as a rule, the blood components could be released on the day of donation.

CONCLUSION

The TaqMan HCV RT-PCR is an almost completely automated, highly sensitive, specific, and rapid method that is reliable for HCV RNA screening of blood donations. It allows a closed-tube HCV RNA detection without risk of contamination by PCR products.

Will genome detection replace serology in blood screening for microbial agents?

The residual risk of transfusion-transmitted viral infection in developed countries is considered minimal or negligible. However, zero risk remains a strong political objective. Genomic screening for HCV, HIV and HBV represents a major advance, eliminating infectious blood donations collected during the pre-seroconversion window period, rare cases of immunosilent infections and, possibly, a large spectrum of viral variants. In Western countries, HCV RNA genomic screening started on pools of 16-400 plasma samples from individual donations. Pooling may produce false-positive and false-negative results. Individual donation testing is more suitable to blood screening but requires multiplexing, automation, and affordable cost. Because donations from individuals who are HBV DNA-negative/serologically positive, or those apparently recovered from HCV infection, may remain infectious, it is unlikely that HBsAg, anti-HCV, and anti-HIV will be discontinued when genomic screening is extended to all three viruses. HIV-1 p24 antigen may prove redundant with HIV RNA screening. Anti-HTLV-I and HTLV-II will remain more effective than genomic testing.

Testing of individual blood donations for HCV RNA reduces the residual risk of transfusion-transmitted HCV infection

BACKGROUND

To allow cost-effective RNA testing with NAT techniques, the national authorities of several countries have planned or already introduced tests of mixed specimens, that is, plasma pools.

STUDY DESIGN AND METHODS

High-throughput extraction, amplification, and detection of HCV RNA from individual blood donations were optimized and validated. The feasibility of the method and the frequency of anti-HCV-negative, HCV RNA-positive donations were determined in a prospective study of 27,745 allogeneic and 792 autologous individual donations.

RESULTS

The 50- and 95-percent detection limits of the method were determined at 44 IU per mL and 162 IU per mL, respectively (World Health Organization HCV reference material). When 201 HCV RNA-positive sera were taken as a reference, the sensitivity was 97.5 percent. The assay specificity was determined at 99.77 percent. During a 20-month period, two seronegative blood donors tested positive in HCV PCR. The viral load of these donations was 6 x 10(6) and 3 x 10(7) copies per mL, respectively. Thus, the yield of HCV RNA testing in this study was 7. 63 per 100,000 screened donations (95% CI, 1.25-22.07). In both PCR-positive donors, seroconversion was found in subsequent blood samples.

CONCLUSION

This study compares the feasibility of single-donation HCV RNA screening, with the detection of a relatively high percentage of window-phase donations, to data reported from groups using HCV RNA testing of plasma pools. The relative yield of NAT of individual donations versus minipools should be directly investigated in the near future.